How extensive is swapping out the rear pinion gear? I have an 86 NA model 5 speed.
i want to go to the 4.3 they have at mazdatrix.
there it is
http://www.mazdatrix.com/g7.htm

 

nobody knows eh

ive heard that swapping the diff is easy, whereas the complete rebuild is very challenging.

 

Well, its pretty easy to do it yourself if you have the right tools (dial indicator, pinion depth checker, calipers, etc). Our cars have adjustable bearing depths I believe, so, it would be a matter of adjusting it and correctly setting the backlash/mesh pattern for coast/drive.

Taking it into a 4x4 shop would be a good solution too. they'll charge ya 300 bucks or so to do it if you take the diff in to them.